Guru Tegh Bahadur Institute of Technology
Fourth Semester - EEE
Course Name: Power System – I
Course Code: ETEE – 206
Question Bank
1. Ferranti effect on long lines is experienced
b. 0.375
when it is
c. 1.33
a. Lightly loaded
d. None
b. On full load at unity pf
6. The maximum demand of a consumer is
c. On full load at 0.8pf lag
2kW and his daily energy consumption is 20
d. In all these cases
units. His load factor is:
2. The presence of earth in case of overhead
a. 10%
lines:
b. 41.6%
a. Increases the capacitance
c. 50%
b. Increases the inductance
d. None
c. Decreases the capacitance
d. Decreases the inductance
3. For an existing ac transmission line, the
7. Sheaths are used in cables to
a. Provide proper insulation
b. Provide mechanical strength
string efficiency is 80%. Now if DC voltage
c. Prevent ingress of moisture
is supplied for the same set-up, the string
d. None
efficiency will be:
8. Corona loss is less when the shape of the
a. 80%
conductor
b. More than 80%
a. Circular
c. Less than 80%
b. Flat
d. 100%
c. Ovel
4. The leakage resistance of a 50km long
cable is 1MΩ. For a 100km long cable, it will
d. Independent of shape
9. The sending end voltage of a feeder with
be:
reactance 0.2pu is 1.2pu. If the reactive
a. 1MΩ
power supplied at the reciving end of the
b. 2MΩ
feeder is 0.3pu, the approximate voltage
c. 0.66MΩ
drop in the feeder is
d. None
a. 0.2pu
5. The connected load of a consumer is 2kW
b. 0.06pu
and his maximum demand is 1.5kW. The
c. 0.05pu
load factor of the consumer is
d. 0.072pu
a. 0.75
Faculty: Harshpreet Kaur
10. The capacitance of a 3-core cable between
b. 1.088pu
any two conductors with sheath earthed is
c. 1.116pu
2µF. The capacitance per phase will be
d. None
a. 1 µF
16. The impedance of a circuit is given by
b. 4 µF
z=3+j4, its conductance is given by:
c. 0.667 µF
a. 1/3
d. 1.414 µF
b. 3/5
11. Three insulating materials with same
maximum working stress and permittivity
2.5, 3.0, 4.0 are used in single core cable.
c. 3/25
d. 4/5
17. In a circuit, the voltage and current are
The location of the materials with respect to
given by v= 10+j5 and i=6+j4. The circuit is
the core of the cable is
a. Inductive
a. 2.5, 3.0, 4.0
b. Capacitive
b. 3.0, 2.5, 4.0
c. Resistive
c. 4.0, 3.0, 2.5
d. Any of above
d. 4.0, 2.5, 3.0
12. A transmission line of 210km length has
18. The power in the above question circuit is
a. 60W
certain values of parameters A, B, C, D. If
b. 20W
the length is made 100km, thus parameter
c. 80W
is
d. 70W
a. A increases, B decreases
b. A decreases, B also decreases
c. A and B both increase
d. A decreases, B increases
13. In the above question
19. The reactive power in the above problem is
a. 70Vars
b. 60vars
a. C increases, D decreases
c. 10vars
b. C and D both decrease’
d. -10vars
c. C and D both increase
d. C decreases, D increases
14. The voltage and current in a circuit are
20. A 100km transmission line is designed for a
nominal voltage of 132kV and consists of
one conductor per phase. The line
given by v = 10sin(wt-π/6), i=10sin(wt+ π/6).
reactance is 0.726Ω/km. The static
The power consumed is given as
transmission capacity of the line, in MW
a. 100W
would be:
b. 50W
a. 132
c. 86.6W
b. 240
d. 25W
c. 416
15. A 60Hz 320km lossless line has sending
end voltage 1.0pu. The reciving end voltage
on no load is
d. 720
21. The per unit impedance of a circuit element
is 0.15. If the base kV and base MVA are
a. 1.1pu
Faculty: Harshpreet Kaur
halved, then the new value of per unit
impedance of the circuit element will be
d. 0.6lag
27. The impedance of a generator is 0.2pu on a
a. 0.075
base value of 11kV, 50MVA. The
b. 0.15
impedance value for a base value of 22kV,
c. 0.30
150MVA is
d. 0.60
a. 0.15pu
22. If the effect of earth is taken into account,
b. 0.2pu
then the capacitance of line to ground
c. 0.3pu
a. Decreases
d. 2.4pu
b. Increases
28. For a transmission line with resistance R,
c. Remains unaltered
reactance X, and negligible capacitance, the
d. Becomes infinite
transmission constant A is
23. A 66kV string insulator having five discs and
a. 0
the earth to disc capacitance ratio of 0.1.
b. 1
The string efficiency will be
c. R+jX
a. 89%
d. R+X
b. 75%
29. A short transmission line having its line
c. 67%
impedance angle as θ, delivering a given
d. 55%
power at the receiving end at a lagging pf
24. Corona loss can be reduced by the use of
angle of Φ. Which of the following
hollow conductor, because
conditions gives maximum regulation:
a. The current density is reduced
a. Φ = θ/2
b. The eddy current in the conductor is
b. Φ – θ = π/2
eliminated
c. For a given cross-section, the radius of
the conductor is increased
d. Of better ventilation of the conductor
25. Transmission lines are transposed to
c. Φ = θ
d. Φ + θ = π/2
30. In the above question which of the following
gives zero regulation?
a. Φ – θ = π/2
a. Reduce copper loss
b. Φ = θ
b. Reduce skin effect
c. Φ + θ = π/2
c. Prevent interference with telephone
d. Φ = θ/2
lines
d. Prevent short circuit
26. A single phase transmission line of
31. Bundles conductors in EHV transmission
system provide:
a. Reduced capacitance
impedance j0.8Ω supplies a resistive load of
b. Increased capacitance
500A at 300V. The sending end power
c. Increased inductance
factor is:
d. Increased voltage gradient
a. Unity
32. The charging current in a transmission line
b. 0.8lag
increases due to corona effect because
c. 0.8lead
corona increases
Faculty: Harshpreet Kaur
a. Line current
37. For a given power delivered, if the working
b. Effective line voltage
voltage of a distributor line is increased to n
c. Power loss in lines
times, the cross-sectional area A of the
d. Effective conductor diameter
distributor line, would be reduced to
33. A power plant has a mximum demand of
a. 1/n * A
15MW. The load factor is 50% and the plant
b. 1/n2 * A
factor is 40%. The operating reserve is:
c. 1/2n2 * A
a. 3MW
d. 1/2n * A
b. 3.75MW
38. When bundle conductors are used in place
c. 6MW
of single conductors, the effective
d. 7.5MW
inductance and capacitance will respectively
34. Galloping in transmission line conductors
a. Increase and decrease
arises generally due to
b. Decrease and increase
a. Asymmetrical layers of ice formation
c. Decrease and remain unaffected
b. Vortex phenomenon in light winds
d. Remain unaffected and increase
c. Heavy weight of line conductors
d. Adoption of horizontal conductor
configurations
35. The per unit impedance of a synchronous
39. For a transmission line with negligible
losses, the lagging var delivered at the
receiving end, for a given receiving end
voltage is directly proportional to the
machine is 0.242. If the base voltage is
a. square of the line voltage drop
increased by 1.1 times, the per unit value
b. line voltage drop
will be
c. line inductive reactance
a. 0.266
d. line capacitive reactance
b. 0.242
40. The inductance of a three phase
c. 0.220
transmission line is 1.2mH/phase/km. If the
d. 0.200
spacing of conductors and the radius of the
36. The self inductance of a long cylindrical
conductor are doubled, then the inductance
conductor due to its internal flux linkages is
of the line will be
k H/m. If the diameter of the conductor is
a. 4.8mH/phase/km
doubled, then the self inductance of the
b. 1.2mH/phase/km
conductor due to its internal flux linkages
c. (ln2)*1.2mH/phase/km
would be
d. (ln4)*1.2mH/phase/km
a. 0.5k H/m
41. A 3 phase transmission line of negligible
b. K H/m
resistance and capacitance has an inductive
c. 1.414k H/m
reactance of 100Ω/phase. When the
d. 4k H/m
sending end and receiving end voltages are
maintained at 100kV, the maximum power
that can be transmitted will be
a. 121MW
b. 121√3
Faculty: Harshpreet Kaur
c. 363MW
b. Ellipse
d. 363kW
c.
42. A string insulator has 4 units. The voltage
across the bottom - most unit is 33% of the
Parabola
d. Circle
46. At slack bus, which of the following are
total voltage. Its string efficiency is
specified?
a. 25%
a. IVI, δ
b. 33.33%
b. P, Q
c. 66.7%
c.
d. 75%
d. Q, IVI
43. The design of insulation for systems above
P, IVI
47. Ring main distribution is preferred to a
400kV, is based upon
radial system because
a. Lightening overvoltage
a. Voltage drop in the feeder is less
b. Switching surges
c. System voltage level
and supply is more reliable
b. Voltage drop is less and power
d. System load level
44. A 50Hz 3 phase transmission line of length
factor is high
c.
100km has a capacitance of 0.03/π, µF per
km. It is represented a π model. The shunt
more reliable
d. Power factor is high and system is
admittance at each end of the transmission
line will be
a.
Power factor is high and supply is
less expensive
48. For a given base voltage and base volt-
150*10-6
angle
900 mho
amperes, the per unit impedance value
b. 1o0*10-6 angle 900 mho
of an element is x. The per unit
c. 50*10-6 angle 900 mho
impedance value of this element when
d.
106/150
angle
900 mho
e. The principal information obtained from
the voltage and volt-ampere bases are
both doubled will be
load flow studies in a power system are:
a. 0.5x
(i) Magnitude and phase angle of the
b. X
voltage at each bus, (ii) Reactive and
c.
real power flow in each line, (iii) Total
d. 4x
power loss of the network, (iv) Transient
2x
49. In load flow studies of a power system,
stability limit of the system
a voltage control bus is specified by
Choose the correct one:
a. P and Q
a. i and ii
b. P, IVI
b. iii and iv
c.
c.
d. Q, IVI
I, ii, and iii
d. ii and iv
IVI, δ
50. The reactance of a generator
45. For fixed sending end and receiving end
designated X” is given as 0.25pu based
voltages in a transmission system, what
on generator’s name plate rating 18kV,
is the locus of constant power
500MVA. If the base for calculations is
a. Straight line
changed to 20kV, 100MVA, the
Faculty: Harshpreet Kaur
generator reactance X” on new base will
be
a. 1.025pu
b. 0.05pu
c.
0.0405pu
d. 0.25pu
Faculty: Harshpreet Kaur